2017MNRAS.472.2670S

Query : 2017MNRAS.472.2670S

2017MNRAS.472.2670S - Mon. Not. R. Astron. Soc., 472, 2670-2685 (2017/December-2)

The shapes and alignments of the satellites of the Milky Way and Andromeda.

SANDERS J.L. and EVANS N.W.

Abstract (from CDS):

We measure the intrinsic shapes and alignments of the dwarf spheroidal (dSph) galaxies of the Local Group. We find the dSphs of the Milky Way are intrinsically flatter (mean intrinsic ellipticity µE ∼ 0.6) than those of M31 (µE ∼ 0.5) and that the classical Milky Way dSphs (MV < -8.5 mag) are rounder (µE ∼ 0.5) than the ultrafaints (µE ∼ 0.65) whilst in Andromeda (M31) the shapes of the classical and ultrafaint dSphs are very similar. The M31 dSphs are preferentially radially aligned with a dispersion of ∼45°. This signal is driven by the ultrafaint population whilst the classical M31 dSphs are consistent with a random orientation. We compare our results to the Aquarius mock stellar catalogues of Lowing et al. and find the subhalo radial alignment distribution matches the Local Group dSphs results, whilst the Aquarius intrinsic ellipticities are significantly smaller than the data (Δ<E> ≃ 0.4). We provide evidence that the major axes of the Milky Way satellites lie within a preferential plane with normal vector pointing towards (ℓ,b)=(127,5)°. We associate this preferred direction with the Vast Polar Orbital structure although their respective great circles are offset by 30. No signal in the alignments of the major axes is found in M31, suggesting that the great plane of satellites is formed from recent accretion or chance alignment. Finally, we provide predictions for the discrepancy between the velocity dispersion versus scale radius distributions for the Milky Way and M31 populations and demonstrate that the projection effect from viewing similar populations from two different locations does not account for the discrepancy which is probably caused by increased tidal disruption in M31.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): galaxies: dwarf - galaxies: fundamental parameters - galaxies: kinematics and dynamics - Local Group - galaxies: structure - galaxies: structure

Simbad objects: 69

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Number of rows : 69
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Andromeda XX G 00 07 30.70 +35 07 56.4     18.2     ~ 77 0
2 And XIX G 00 19 32.10 +35 02 37.1     15.6     ~ 168 0
3 NAME Andromeda XXVI G 00 23 45.6 +47 54 58     17.3     ~ 76 0
4 NAME Andromeda XXV G 00 30 08.9 +46 51 07     14.8     ~ 120 0
5 NAME Magellanic Stream HVC 00 32 -30.0           ~ 1079 1
6 NAME Andromeda III G 00 35 33.8 +36 29 52     14.4     ~ 309 0
7 NAME Cassiopeia III G 00 35 59.4 +51 33 35           ~ 59 0
8 NAME Andromeda XXX G 00 36 34.90 +49 38 48.0           ~ 59 0
9 NAME Andromeda XVII G 00 37 07.0 +44 19 20     15.8     ~ 101 0
10 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
11 NAME Andromeda I G 00 45 39.8 +38 02 28   13.9 12.7     ~ 355 0
12 NAME Andromeda XI G 00 46 20.0 +33 48 05     17.5     ~ 130 0
13 NAME Andromeda XII G 00 47 27.0 +34 22 29     18.3     ~ 124 0
14 NAME Andromeda XIV G 00 51 35.0 +29 41 49     15.9     ~ 132 0
15 NAME Andromeda XIII G 00 51 51.0 +33 00 16     18.1     ~ 128 0
16 NAME Andromeda IX G 00 52 53.0 +43 11 45     16.3     ~ 176 1
17 NAME Pisces V G 00 59 29.8 +32 22 36     14.4     ~ 149 0
18 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
19 NAME Andromeda X G 01 06 33.70 +44 48 15.8     16.6     ~ 125 1
20 NAME Andromeda V G 01 10 17.1 +47 37 41     15.3     ~ 215 0
21 NAME Andromeda XV G 01 14 18.7 +38 07 03     14.6     ~ 123 0
22 NAME Andromeda II G 01 16 29.8 +33 25 09     11.7     ~ 402 0
23 NAME Andromeda XXIV G 01 18 30.0 +46 21 58     16.3     ~ 64 0
24 NAME Andromeda XXII G 01 27 40.0 +28 05 25     18.0     ~ 95 0
25 NAME Andromeda XXIII G 01 29 21.8 +38 43 08     14.2     ~ 88 0
26 NAME Tri II G 02 13 17.40 +36 10 42.4           ~ 164 0
27 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 299 0
28 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
29 NAME Hor I G 02 55 31.7 -54 07 08           ~ 169 0
30 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
31 NAME Andromeda XXXIII G 03 01 23.6 +40 59 18           ~ 43 0
32 NAME Horologium II G 03 16 32.1 -50 01 05           ~ 76 0
33 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 375 0
34 NAME Eridanus II G 03 44 21.1 -43 32 00           ~ 216 0
35 ESO 206-20A G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 1190 0
36 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
37 NAME Leo T G 09 34 53.4 +17 03 05     15.1     ~ 434 0
38 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
39 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1284 1
40 NAME Sextans dSph LSB 10 13 02.9 -01 36 53   12 10.4     ~ 921 0
41 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
42 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
43 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 899 0
44 NAME Leo V LSB 11 31 09.60 +02 13 12.0     16.0     ~ 234 0
45 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
46 NAME Crater II Dwarf Galaxy G 11 49 14 -18 24.8           ~ 176 0
47 NAME Hydra II G 12 21 42.1 -31 59 07           ~ 118 0
48 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
49 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1274 0
50 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
51 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
52 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 269 0
53 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
54 Z 318-18 G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1459 0
55 NAME Draco II Gl? 15 52 47.6 +64 33 55           ~ 138 0
56 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 379 1
57 Z 300-12 G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1428 1
58 NAME SDG G 18 55 19.0 -30 32 43   4.5 3.6     ~ 2438 2
59 NAME Pegasus III LSB 22 24 22.6 +05 25 12           ~ 69 0
60 NAME Aquarius 2 G 22 33 55.5 -09 19 39           ~ 66 0
61 NAME Tuc II G 22 51 55.1 -58 34 08           ~ 192 0
62 NAME Grus I G 22 56 42.4 -50 09 48           ~ 126 0
63 NAME Lacerta I G 22 58 16.3 +41 17 28           ~ 53 0
64 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 283 0
65 NAME Andromeda VII GiG 23 26 31.0 +50 40 33   13.6 11.8     ~ 222 1
66 NAME Peg dSph GiG 23 51 46.3 +24 34 57   14.5 13.2     ~ 250 2
67 NAME Andromeda XXI G 23 54 47.7 +42 28 15     14.8     ~ 117 0
68 NAME Andromeda XXIX G 23 58 55.6 +30 45 20     16.0     ~ 61 0
69 NAME Local Group GrG ~ ~           ~ 9325 0

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